PO needle set up

[Good Times]

Ok fellas. I've got the bike together and running. Carbs cleaned, new o-rings, synced. Rode a little today to see how she would run.

As a reminder here's my set up:

82 850 GL
K&N Pods
V&H 4 into 1
DJ Stage 3 Kit
Clips on the third grove from the top of the needle
Needles 4 1/2 turns out per the DJ instructions


The bike runs great. It is smooth and pulls all the way to redline. No stumble, no flat spots. I love it.

I am getting some backfire through one or more carbs (can't really tell which one or ones) when I'm running somewhere around 3000 or 4000. It's not constant but intermittent. I get a little hesitation with the popping.

I also get popping on decel, but am fully aware that I need new exhaust gaskets and that my V&H isn't air tight at the collector. Easy enough fix.

I have searched and seen a thread on the "cough" "popping" "backfire" on a lot of bikes. I don't think I've seen anything that was a fix yet. I've thought about setting my needles back down one turn to 3 1/2 turns out rather than 4 1/2 and see what that does.

Anyone had this and made it disappear or improve it?

[gearhead13]

Popping on decel is a lean mixture, no air leaks? new carb boot o-rings? Try a bigger pilot jet or richen the mixture screws some. Have the valves been adjusted?

[koolaid_kid]

Most likely plug chops will indicate a cylinder or two that may need a bit of fine tuning. All four cylinders will not run the same with the same carb settings. This is why the serious racers put a wideband O2 sensor in every pipe rather than in the collector.

[Good Times]

Popping on decel is a lean mixture, no air leaks? new carb boot o-rings? Try a bigger pilot jet or richen the mixture screws some. Have the valves been adjusted?

Yes. New boots and orings. It popped before on decel and the mixture was crazy rich. Take a look at how the needles were set up at the beginning of this thread. That along with 170 mains was way rich.

Most likely plug chops will indicate a cylinder or two that may need a bit of fine tuning. All four cylinders will not run the same with the same carb settings. This is why the serious racers put a wideband O2 sensor in every pipe rather than in the collector.

Haven't done a plug chop yet. It's either that or drill and tap some sensor holes in my header. No popping on decel then right?

[koolaid_kid]

Haven't done a plug chop yet. It's either that or drill and tap some sensor holes in my header. No popping on decel then right?

Well, there are no guarantees on anything, including life. But it will allow you to set every cylinder the same. For similar results without the drilling, reading plugs should get you close. Besides, popping indicates that you have a hot bike, right?